In general, in studies in the fields of physics, chemistry and material, it is very important to measure optical properties of a material and measure a thickness of a thin film. Particularly, a variety of nano-thin film manufacturing processes is used in semiconductor industries, and an ellipsometer which is non-destructive and contactless real-time measuring equipment is widely used as a measuring equipment to evaluate physical properties of the manufactured thin films.
A variety of methods is currently known as a principle of measuring optical properties of a material and a thickness of a thin film. An ellipsometry has largely increased applications as its performance is much improved with development of a light source, a photodetector and a computer and processes using a thin film and a surface are increased. Also, a Scanning Probe Microscope (hereinafter, referred to as “SPM”) is an instrument capable of measuring the surface of the material at an atomic level and used in wide application fields.
The ellipsometry can be divided into a reflection type and a transmission type and the widely used is the reflection type ellipsometry which analyzes a polarization state of a light reflected from a surface of a specimen with an angle of incidence. By measuring variation in the polarization state of the light reflected by the specimen, it may be used mainly to extract the optical properties of the specimen such as a refractive index or an extinction coefficient and may be used to extract properties such as interfacial state of the specimen as well.
In the case of focusing on the surface of the specimen in a dot shape using an optical system, a plurality of the specimens cannot be measured at the same time and thus it takes much time since the thickness or properties of the specimen has to be measured one after another.
Also, in the case of measuring the optical properties of the specimen with an ellipsometer, it is difficult to measure the very minute optical properties of the specimen since its horizontal resolution is low. In this case, it is possible to measure the minute optical properties of the specimen using a microscope having excellent vertical and horizontal resolutions such as a SPM, but it takes much time to measure the minute optical properties of the specimen since the ellipsometer and the SPM are constructed as separate instruments. In other words, it is possible to find a singular point using the ellipsometer, but a large area has to be minutely measured again, as it is difficult to know the exact position of the singular point when measuring using the SPM after the measurement of the ellipsometer, and the SPM constructed as a separate instrument has to be provided. Therefore, it takes much time and efforts.